Electro-mechanical latch relay

ABSTRACT

A mechanical latch relay started by a current pulse is disclosed which comprises an electromagnetic generating unit, a connecting mechanism and a mechanical locking mechanism, and which can maintain the existing operation state when the current pulse starting the relay disappears, and it changes its operation state when another current pulse is provided, and then it keeps the operation state even if the pulse disappears so that it can provide a stable operation state of current on/off unnecessary to be provided with a current for a long time, which enables to provide an effective control for current on/off.

FIELD OF THE INVENTION

The present invention relates to a mechanical latch relay started by alatch current pulse, and more particularly, a relay having a mechanicallocking means for keeping the operation states provided by the currentpulse.

BACKGROUND OF THE INVENTION

At present, most of the commercial relays, when provided with anoperation current, can change their output states, e.g. from “on” to“off” or from “off” to “on”, and will return to their original stateswhen the current provided disappears. In order to maintain the changedstates, the current must be provided constantly. An improved relay is onthe market to overcome this drawback which needs only a single pulse tokeep the changed state. The most relative prior art is the latch relaymanufactured by COLE HERSEE CO., U.S.A., but it is complicated, large,and unstable in operation since it requires three springs.

SUMMARY OF THE INVENTION

The present invention provides at least a mechanical latch relayactivated by a latch current pulse in which a mechanical locking meansallows an operating current to maintain its present operating state ofthe latch relay when the latch current pulse is removed and changes itsoperating state of the latch relay when another latch current pulse isprovided, and then keeps the new operating state when the latch currentpulse is removed thereby eliminating the necessity to continuouslyprovide the latch current pulse for a particular operating state.

The present invention further provides at least a mechanical latch relaystarted activated by a latch current pulse, which provides a stableoperating state of on/off current for effective control of on/offcurrent.

The present invention further provides at least a mechanical latch relaystarted by a very short latch current pulse.

The present invention further provides at least a mechanical latch relaywhich is convenient to operate, time and energy efficient, simple instructure, cheap to manufacture, and which may enable large current.

To achieve the above objects, the present invention provides amechanical latch relay comprising a casing with two connecting holes ona side thereof for receiving a latch current pulse metal plates on abottom thereof for connecting to an external circuit a cavity includingat a center of the bottom side grooves and a cover on an upper endthereof; an electromagnetic generating unit, a connecting means and alocking means housed within said casing, said electromagnetic generatingunit includes a coil assembly for generating an electromagnetic fieldincluding a central bore and a rotor spring positioned in said centralbore; said connecting means includes a connecting plate having a bolt onone side of said connecting plate and a columnar rotor which is insertedinto said rotor spring on the other side thereof, said locking meanscomprises a small spring positioned in said cavity a locking componentplaced on said small spring and a clamping part with clamping tabs; saidlocking component is a cylinder having teeth at one end thereof forengaging with said clamping tabs and a gear on the periphery thereof forengaging with side grooves of said cavity.

The advantages of the present invention lie in that it can provide astable operating state for on/off current, and it enables an effectivecontrol for on/off current. Moreover, since the metal plate forconnecting with an external circuit is made of special material, therange of output current is greatly extended, e.g. from 0 to 250 A.

DESCRIPTION OF THE DRAWINGS

An embodiment of the present inventionl will described with the attacheddrawings, in which:

FIG. 1 is a perspective view of a latch relay according to the priorart;

FIG. 2 is a sectional view of the latch relay according to the priorart;

FIG. 3 is a schematic perspective view of a casing of a mechanical latchrelay of the present invention;

FIG. 4 is an exploded view of an electromagnetic generating unit, aconnecting means, a mechanical locking means, and a casing of amechanical latch relay of the present invention;

FIG. 5A is an enlarged perspective view of a U-plate of the mechanicallatch relay of the present invention;

FIG. 5B is a sectional view of the U-plate of the mechanical latch relayof the present invention illustrated in FIG. 5A taken along line 5B—5B;

FIG. 6A is a top view of a connecting plate of the mechanical latchrelay of the present invention;

FIG. 6B is a side view of the connecting plate of the mechanical latchrelay of the present invention;

FIG. 7A is an enlarged perspective view of a clamping element of themechanical latch relay of the present invention;

FIG. 7B is a bottom view of the clamping element of the mechanical latchrelay of the present invention shown in FIG. 7A;

FIG. 8A is an enlarged perspective view of a locking component of themechanical latch relay of the present invention;

FIG. 8B is a top view of the locking component of the mechanical latchrelay of the present invention shown in FIG. 8A;

FIG. 9A is a sectional view of a locking cavity of the mechanical latchrelay of the present invention;

FIG. 9B is a top view of the locking cavity of the mechanical latchrelay of the present invention shown in FIG. 9A;

FIG. 10A is a sectional view of the mechanical latch relay of thepresent invention shown in FIG. 3 taken along line 10A—10A in an outputcurrent “off” state;

FIG. 10B is a sectional view of the mechanical latch relay of thepresent invention shown in FIG. 10A taken along line 10B—10B in anoutput current “off” state;

FIG. 11 is a sectional view of the mechanical latch relay of the presentinvention shown in FIG. 3 taken along line 11—11, showing current “off”state turning the mechanical latch relay when a latch current pulse isprovided;

FIG. 12A is a sectional view of the mechanical latch relay of thepresent invention shown in FIG. 3 taken along line 12A—12A, in an outputcurrent “on” state;

FIG. 12B is a sectional view of the mechanical latch relay of thepresent invention shown in FIG. 12 A taken along line 12B—12B, in anoutput current “on” state.

DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 show a latch relay according to the prior art,manufactured by COLE HERSEE CO., U.S.A., which has an external size 80mm×85 mm×62 mm, and which has a large volume, a complicated structureand is unstable in operation since it requires three springs.

Referring to FIGS. 3 and 4, the mechanical latch relay of the presentinvention includes a casing 60 for containing an electromagneticgenerating unit that produces a magnetic field, a connecting means and alocking means for maintaining a current on/off states (discussed indetail below). Two projecting metal plate 61 for connecting to anexternal circuit are provided on the bottom of the casing 60, the metalplates 61 may be made of pure copper coated with tin. The other end ofeach metal plate 61 is inlaid on the bottom of casing 60 by a rivet madeof silver alloy whose head 62 projects inwards from the bottom of thecasing. Moreover, on the inside bottom of the casing 60, in addition tothe two rivet heads for connecting to an external circuit, there is acontact 69 providing a third contact point for contacting a connectingplate. The third contact point may also connect a detecting circuit soas to monitor the on/off state of the current to an external circuit. Onthe center of the bottom of casing 60 there is a cavity 70 whichprojects outwards and is provided with grooves in its interior wall forengaging with the locking component of the locking means. Two coilconnecting holes 68 used for transmitting a latch current pulse to thecoil assembly are installed on one side of casing 60. On the other endof casing 60 is a cover 65, both casing 60 and cover 65 are made ofsuperior quality polyethylene through die casting, and are solderingsealed by ultrasonic technology.

FIG. 4 is a schematic view showing the interior parts of a mechanicallatch relay of the present invention. The relay comprises a coilassembly 100 made of polyurethane insulated copper wire 13 wound about areel 11 made of polysulfone through casting, both ends of copper wire 13extending out connecting holes 68 in one side of the casing andconnecting to a source of the latch current pulse. In the middle of reel11 is an axle hole 12 in which a rotor spring 90 is positioned.Referring to FIGS. 4, 5A and 5B, a U-iron plate 80 presses upon an upperend of the coil assembly 100, and on another end of the coil assembly100 there is a magnetic field occlusor 10 which cooperates with U-ironplate 80 to enclose the coil assembly 100 so that a closed magneticcircuit is generated when a latch current pulse passes through thecopper wire 13 which enhances the magnetic force. In the center of theU-iron plate 80 there is an inward projecting column 81 whose diameterand position are designed in such a way that the column 81 cancomplementarily engage the rotor spring 90. An inward projecting conicgroove 82 is provided at one end of column 81, as shown in FIG. 5B. Therotor spring 90 is made of superior quality steel coated with nickel.

The connecting means includes a magnetic field augment piece 21 and aconnecting plate 20 secured to the augment piece 21. A column isinstalled at the center of magnetic field augment piece 21 andconnecting plate 20. One end of the column is a columnar rotor 22 andthe other end is a bolt 25 having a relative thickness less than therotor 22. One end of columnar rotor 22 is shaped as outer cone 27matching the inward projecting conic groove 82 of column 81 mounted onthe U-iron plate 80. During installation columnar rotor 22 insertsthrough a hole 13 of magnetic field occlusor 10, into the rotor spring90 positioned in coil assembly 100 axle hole 12 with the inwardprojecting conic groove 82 of column 81 matching well with the outercone 27 at the end of columnar rotor 22. Thus, when the electromagneticgenerating unit consisting of the U-iron plate 80, coil assembly 100,and magnetic field occlusor 10 generates a magnetic field and magneticforce upon receiving the latch current pulse the U-iron plate 80 and themagnetic field augment piece 21 press against the elastic force of therotor spring 90 of coil assembly 100 under the magnetic force, with theinward projecting conic groove 82 of column 81 closely fitting withouter cone 27 at the end of the columnar rotor 22. When the latchcurrent pulse is removed, the magnetic force fades away concurrently,and the U-iron plate 80 and the magnetic field augment piece 21 move inthe opposite direction due to the elastic force of the rotor spring 90,thereby the inward projecting conic groove 82 of column 81 separatesfrom the outer cone 27 at the end of the columnar rotor 22.

Referring now to FIGS. 6A and 6B a shallow slot 26 is provided in oneend of the connecting plate 20 on the same side of the bolt 25 forcontaining a metal slab 28 which has the features of high electricconductivity, high thermal conductivity, high resistance to electricarc, high mechanical stability, high hardness, and light weight, etc.,so as to facilitate switching on larger current output. The metal slab28 is made of silver-copper alloy, for example, 92.5% silver and 7.5%copper. When the metal slab 28 contacts a rivet head 62 at the internalend of the casing for securing the external circuit board, the externalcircuit is switched on. As illustrated in FIGS. 6A, 6B, the connectingplate 20 may be made into a triangular shape so as to reduce its weightand volume.

The mechanical latch relay of the present invention is provided with alocking means which comprises a small spring 50 positioned in a lockingcavity 70 of the casing 60, a locking component 40 placed on the smallspring 50, and a clamping part 30; the clamping part 30 has columnarshape, at the center of one end of which is an inner hole 31 forreceiving bolt 25, and on the periphery of which are evenly distributedevery 120° three clamping tabs 32 the bottom edges of the clamping tabs32 form a slope 35; a small column head 33 is located at the center ofthe other end of the clamping part 30 for insertion into a hollow holeof the locking component 40, as shown in detail in FIGS. 7A and 7B. Thelocking component 40 is a hollow cylinder, provided with teeth 41 at oneend thereof whose shape and size match the slope 35 of the clamping tabs32, a bead 43 with a smaller diameter than the other end thereof, and agear 42 on the periphery thereof, whose shape and size match the sidegrooves 72 on the interior wall of cavity 70 in casing 60, as shown indetail in FIGS. 8A and 8B. The component 40 and the clamping part 30 aremade of polyvinylacetate through casting which has good thermalstability, and the surface that engages with the cavity 70 is made ofcopper-nickel alloy, which may extend its service life.

FIGS. 9A, 9B illustrate the locking cavity 70 of the casing 60 whichincludes interior circumstance wall having ribs 75 with end faces 73,half grooves 71 and full grooves 72. When the clamping tabs 32 areclamped in half grooves 71, the metal slab 28 on the connecting plate 20does not contact the rivet head 62 in the casing 60 and the externalcircuit is switched off. When the clamping tabs 32 are positioned in thebottom of full grooves 72, the metal slab 28 on the connecting plate 20contacts the rivet head 62 in the casing 60 and the external circuit isswitched on.

Now the operating principle of the mechanical latch relay of the presentinvention will be explained with the attached drawings.

First referring to FIGS. 10A, 10B, the metal slab 28 on the connectingplate 20 does not contact the rivet head 62 in the casing, and thereforethe external circuit is in a “turn-off” state. At this time, theclamping tabs 32 of the clamping part 30 engage the half grooves 71 inthe cavity 70 and the rotor spring 90 located between the magnetic fieldocclusor 10 and the U-iron plate 80 assumes a half-pressed status. Anelastic force is transmitted to the clamping part 30 via the columnarrotor 22 and the bolt 25. The small spring 50 also exerts a force to theclamping part 30 via the locking component 40 so as to enable theclamping tabs 32 to be firmly clamped on the half grooves 71 withoutrotation.

Referring to FIG. 11, now a latch current pulse is transmitted to thecoil assembly 100 through coil connecting holes 68, which generates amagnetic field with different polarities at both ends of the coil. Dueto magnetic force attraction, the U-iron plate 80 and magnetic fieldaugment piece 21 press onto the coil assembly 100 against the elasticforce of the rotor spring 90, and the inward projecting conic groove 82of column 81 leading out from the U-iron plate 80 closely fits with theouter cone 27 at the end of the columnar rotor 22. At the moment, theelastic force of the small spring 50 pushes the clamping tabs 32 out ofthe half grooves 71 in the cavity 70 through the locking component 40.Due to the movement between the slope 35 of the clamping tabs 32 and theteeth 41 of the locking component 40 and the action of the rotor springs90, the clamping part 30 performs a tiny rotation, which enables an apexof the slope 35 to stick against the end face 73 of a rib, slide downalong it and rotate (along the arrow direction in FIG. 10B), until theclamping tabs 32 align with the full grooves 72, referring also to FIG.9A.

Finally referring to FIGS. 12A and 12B, when a latch current pulse isremoved, a repulsive force is generated upon magnetic field variationwhich, together with an elastic force of the rotor spring 90, pushes theconnecting plate 20 to the bottom. Since the clamping tabs 32 arealready aligned with the full grooves 72 in the cavity 70, it can movetoward the bottom of the cavity 70 without resistance so as to enablethe connecting plate 20 to contact with rivet head 62, and the externalcircuit is switched on.

If another latch current pulse comes due to the magnetic force, theU-iron plate 80 and the magnetic field augment piece 21 press down onthe coil assembly 100 again, the connecting plate 20 separates from therivet head 62, and the circuit is turned off. At that moment, theclamping tabs 32 are pushed out from the full grooves 72 in the cavity70 by the elastic force of the small spring 50. Similarly, due to themovement between the slope 35 of the clamping tabs 32 and the teeth 41of the locking component 40 and the action of the rotor spring 90, theclamping part 30 performs a tiny rotation, which enables an apex ofslope 35 to stick against the end face 73 of another rib, slide downalong it and rotate (along the arrow direction in FIG. 10B), until theclamping tabs 32 are aligned with the half grooves 71. When the latchpulse current pulse is removed due to the action of a magnetic fieldrepulsive force and an elastic force of the rotor spring 90, theclamping tabs 32 are pushed into the half grooves 71. At that moment,the circuit maintains “off” state until the next pulse appears.

In summary, when a latch current pulse is input to the relay of thepresent invention, the state of the external circuit varies. Then, evenif the latch pulse current pulse is removed, the status will beretained. A latch current pulse needs to be input again to change thestatus of the external circuit. Thus, a stable operating status ofcurrent on/off is provided, which enables an effective control forcurrent on/off.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification, as indicating the scope of theinvention.

What is claimed is:
 1. A mechanical latch relay activated by a latchcurrent pulse, comprising: a casing (60), connectable to a currentsource, the casing including a bottom, a plurality of side walls and acover (65) forming a generally closed cavity; at least two metal plates(61) extending from the bottom for connecting to an external circuit,each metal plate including a contact element (62) extending into thecasing cavity; a generally cylindrical housing forming a cavity (70),the housing cavity open to the casing cavity, the housing cavityincluding side grooves about the interior wall thereof; aelectromagnetic generating unit for generating an electromagnetic fieldpositioned within said casing cavity, said electromagnetic generatingunit including a coil (100) with a central bore (12) co-axial with thehousing cavity; a connecting means movable axially to and from aposition in which it contacts the said contact elements (62); a lockingmeans within said casing, said locking means comprising a lockingcomponent (40) and a clamping part (30) including clamping tabs (32);said locking component (40) being a cylinder provided with teeth (41) atone end thereof for engaging with said clamping tabs (32) and a gear(42) on the periphery of the cylinder positioned within side grooves(71, 72) of said cavity (70); said clamping tabs (32) so engaging saidteeth (41) and the side grooves (71, 72) of the cavity (70) that axialreciprocation of the locking component (40) causes indexed rotation ofthe clamping part (30) between positions in which the connecting means(20) contacts and does not contact the contact elements (62); and a coilspring (90) pressing the clamping part (30) into the side grooves (71,72) of the cavity (70); characterised in that the generally cylindricalhousing extends from a center of the said bottom of the casing (60); theconnecting means includes a connecting plate (20) disposed between theelectromagnetic generating unit and the housing and having a bolt (25)on a first side of said connecting plate and a columnar shaft (22) onthe second side of said connecting plate (20), the columnar shaft (22)positioned within the central bore (12) of the coil (100); the coilspring (90) is positioned within the central bore (12) of the coil (100)and around the columnar shaft (22) and a second spring (50), weaker thanthe coil spring (90), is positioned in the housing cavity (70) andpresses the locking component (40) against the clamping part (30); andthe connecting means (20) is pressed by the said coil spring (90)towards the position in which the connecting plate (20) contacts thesaid contact elements (62), and is moved away from that position bymagnetic force attraction when the electromagnetic generating unit isactivated.
 2. The mechanical latch relay according to claim 1, whereinsaid housing cavity includes ribs (75), half grooves (71) ad fullgrooves (72) on the interior circumferential surface thereof.
 3. Themechanical latch relay according to claim 2, wherein said ribs (75) areprovided with inclined end faces (73).
 4. The mechanical latch relayaccording to claim 3, wherein said clamping tabs (32) include a slope(35) at lower edges thereof engaging with the inclined end faces (73) ofsaid ribs (75).
 5. The mechanical latch relay according to claim 1,wherein said electromagnetic generating unit further comprises a U-ironplate (80) and a magnetic field occlusor (10) mounted on an end of thecoil (100).
 6. The mechanical latch relay according to claim 5, furthercomprising an inner projecting column (81) at the center of said U-ironplate (80), the inner projecting column having a position and diametersuch that it can be introduced into said coil spring (90).
 7. Themechanical latch relay according to claim 1, wherein said connectingmeans further comprises a magnetic field augment piece (21) secured tosaid connecting plate (20).
 8. The mechanical latch relay according toclaim 6, wherein one end of said columnar shaft (22) presents aprojecting conic shape (27) and said inner projecting column (81)includes an inwardly projecting conic groove (82) at the center thereof,positioned to mate with said projecting conic shape of said columnarshaft.
 9. The mechanical latch relay according to claim 1, furthercomprising a shallow slot (26) at one end of said connecting plate (20)on the same side as said bolt (25) and a metal slab (28) positionedwithin said slot.
 10. The mechanical latch relay according to claim 9,wherein said metal slab (28) is made of silver-copper alloy.
 11. Themechanical latch relay according to claim 10, wherein said metal slab(28) is made of 92.5% silver and 7.5% copper.
 12. The mechanical latchrelay according to claim 1, wherein said connecting plate (20) istriangular in shape.
 13. The mechanical latch relay according to claim1, wherein there are three clamping tabs (32) evenly distributed inspacing 120° with each other on the periphery of said clamping part(30).
 14. The mechanical latch relay according to claim 1, wherein saidlocking component (40) and clamping part (30) are made ofpolyvinylacetate with good thermal stability through casting, thesurface thereof abutting with said cavity (70) are made of copper-nickelalloy.
 15. The mechanical latch relay according to claim 1, furthercomprising an inner hole (31) matching said bolt (25) provided at oneend of said clamping part (30) and a projecting small column head (33)provided at the other end thereof.
 16. The mechanical latch relayaccording to claim 15, wherein said locking component (40) is hollow andreceives said small column head (33).
 17. The mechanical latch relayaccording to claim 1, further comprising a bead with a smaller diameterprovided at one end of said locking component (40) secured to saidsecond spring (50).
 18. The mechanical latch relay according to claim 1,further comprising a contact (69) for engaging with said connectingplate (20) provided on the bottom of said casing.